/*
 * Copyright 2017 - 2024 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see [https://www.gnu.org/licenses/]
 */

package infra.context.testfixture.jndi;

import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;

import javax.naming.Binding;
import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NameClassPair;
import javax.naming.NameNotFoundException;
import javax.naming.NameParser;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.OperationNotSupportedException;

import infra.jndi.JndiTemplate;
import infra.lang.Nullable;
import infra.logging.Logger;
import infra.logging.LoggerFactory;
import infra.util.StringUtils;

/**
 * Copy of the standard {@link infra.mock.jndi.SimpleNamingContext}
 * for testing purposes.
 *
 * <p>Simple implementation of a JNDI naming context.
 * Only supports binding plain Objects to String names.
 * Mainly for test environments, but also usable for standalone applications.
 *
 * <p>This class is not intended for direct usage by applications, although it
 * can be used for example to override JndiTemplate's {@code createInitialContext}
 * method in unit tests. Typically, SimpleNamingContextBuilder will be used to
 * set up a JVM-level JNDI environment.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see SimpleNamingContextBuilder
 * @see JndiTemplate#createInitialContext
 */
public class SimpleNamingContext implements Context {

  private final Logger logger = LoggerFactory.getLogger(getClass());

  private final String root;

  private final Hashtable<String, Object> boundObjects;

  private final Hashtable<String, Object> environment = new Hashtable<>();

  /**
   * Create a new naming context.
   */
  public SimpleNamingContext() {
    this("");
  }

  /**
   * Create a new naming context with the given naming root.
   */
  public SimpleNamingContext(String root) {
    this.root = root;
    this.boundObjects = new Hashtable<>();
  }

  /**
   * Create a new naming context with the given naming root,
   * the given name/object map, and the JNDI environment entries.
   */
  public SimpleNamingContext(
          String root, Hashtable<String, Object> boundObjects, @Nullable Hashtable<String, Object> env) {

    this.root = root;
    this.boundObjects = boundObjects;
    if (env != null) {
      this.environment.putAll(env);
    }
  }

  // Actual implementations of Context methods follow

  @Override
  public NamingEnumeration<NameClassPair> list(String root) throws NamingException {
    if (logger.isDebugEnabled()) {
      logger.debug("Listing name/class pairs under [" + root + "]");
    }
    return new NameClassPairEnumeration(this, root);
  }

  @Override
  public NamingEnumeration<Binding> listBindings(String root) throws NamingException {
    if (logger.isDebugEnabled()) {
      logger.debug("Listing bindings under [" + root + "]");
    }
    return new BindingEnumeration(this, root);
  }

  /**
   * Look up the object with the given name.
   * <p>Note: Not intended for direct use by applications.
   * Will be used by any standard InitialContext JNDI lookups.
   *
   * @throws javax.naming.NameNotFoundException if the object could not be found
   */
  @Override
  public Object lookup(String lookupName) throws NameNotFoundException {
    String name = this.root + lookupName;
    if (logger.isDebugEnabled()) {
      logger.debug("Static JNDI lookup: [" + name + "]");
    }
    if (name.isEmpty()) {
      return new SimpleNamingContext(this.root, this.boundObjects, this.environment);
    }
    Object found = this.boundObjects.get(name);
    if (found == null) {
      if (!name.endsWith("/")) {
        name = name + "/";
      }
      for (String boundName : this.boundObjects.keySet()) {
        if (boundName.startsWith(name)) {
          return new SimpleNamingContext(name, this.boundObjects, this.environment);
        }
      }
      throw new NameNotFoundException(
              "Name [" + this.root + lookupName + "] not bound; " + this.boundObjects.size() + " bindings: [" +
                      StringUtils.collectionToDelimitedString(this.boundObjects.keySet(), ",") + "]");
    }
    return found;
  }

  @Override
  public Object lookupLink(String name) throws NameNotFoundException {
    return lookup(name);
  }

  /**
   * Bind the given object to the given name.
   * Note: Not intended for direct use by applications
   * if setting up a JVM-level JNDI environment.
   * Use SimpleNamingContextBuilder to set up JNDI bindings then.
   *
   * @see infra.context.testfixture.jndi.SimpleNamingContextBuilder#bind
   */
  @Override
  public void bind(String name, Object obj) {
    if (logger.isInfoEnabled()) {
      logger.info("Static JNDI binding: [" + this.root + name + "] = [" + obj + "]");
    }
    this.boundObjects.put(this.root + name, obj);
  }

  @Override
  public void unbind(String name) {
    if (logger.isInfoEnabled()) {
      logger.info("Static JNDI remove: [" + this.root + name + "]");
    }
    this.boundObjects.remove(this.root + name);
  }

  @Override
  public void rebind(String name, Object obj) {
    bind(name, obj);
  }

  @Override
  public void rename(String oldName, String newName) throws NameNotFoundException {
    Object obj = lookup(oldName);
    unbind(oldName);
    bind(newName, obj);
  }

  @Override
  public Context createSubcontext(String name) {
    String subcontextName = this.root + name;
    if (!subcontextName.endsWith("/")) {
      subcontextName += "/";
    }
    Context subcontext = new SimpleNamingContext(subcontextName, this.boundObjects, this.environment);
    bind(name, subcontext);
    return subcontext;
  }

  @Override
  public void destroySubcontext(String name) {
    unbind(name);
  }

  @Override
  public String composeName(String name, String prefix) {
    return prefix + name;
  }

  @Override
  public Hashtable<String, Object> getEnvironment() {
    return this.environment;
  }

  @Override
  @Nullable
  public Object addToEnvironment(String propName, Object propVal) {
    return this.environment.put(propName, propVal);
  }

  @Override
  public Object removeFromEnvironment(String propName) {
    return this.environment.remove(propName);
  }

  @Override
  public void close() {
  }

  // Unsupported methods follow: no support for javax.naming.Name

  @Override
  public NamingEnumeration<NameClassPair> list(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public NamingEnumeration<Binding> listBindings(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public Object lookup(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public Object lookupLink(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public void bind(Name name, Object obj) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public void unbind(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public void rebind(Name name, Object obj) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public void rename(Name oldName, Name newName) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public Context createSubcontext(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public void destroySubcontext(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public String getNameInNamespace() throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public NameParser getNameParser(Name name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public NameParser getNameParser(String name) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  @Override
  public Name composeName(Name name, Name prefix) throws NamingException {
    throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
  }

  private abstract static class AbstractNamingEnumeration<T> implements NamingEnumeration<T> {

    private final Iterator<T> iterator;

    private AbstractNamingEnumeration(SimpleNamingContext context, String proot) throws NamingException {
      if (!proot.isEmpty() && !proot.endsWith("/")) {
        proot = proot + "/";
      }
      String root = context.root + proot;
      Map<String, T> contents = new HashMap<>();
      for (String boundName : context.boundObjects.keySet()) {
        if (boundName.startsWith(root)) {
          int startIndex = root.length();
          int endIndex = boundName.indexOf('/', startIndex);
          String strippedName =
                  (endIndex != -1 ? boundName.substring(startIndex, endIndex) : boundName.substring(startIndex));
          if (!contents.containsKey(strippedName)) {
            try {
              contents.put(strippedName, createObject(strippedName, context.lookup(proot + strippedName)));
            }
            catch (NameNotFoundException ex) {
              // cannot happen
            }
          }
        }
      }
      if (contents.size() == 0) {
        throw new NamingException("Invalid root: [" + context.root + proot + "]");
      }
      this.iterator = contents.values().iterator();
    }

    protected abstract T createObject(String strippedName, Object obj);

    @Override
    public boolean hasMore() {
      return this.iterator.hasNext();
    }

    @Override
    public T next() {
      return this.iterator.next();
    }

    @Override
    public boolean hasMoreElements() {
      return this.iterator.hasNext();
    }

    @Override
    public T nextElement() {
      return this.iterator.next();
    }

    @Override
    public void close() {
    }
  }

  private static final class NameClassPairEnumeration extends AbstractNamingEnumeration<NameClassPair> {

    private NameClassPairEnumeration(SimpleNamingContext context, String root) throws NamingException {
      super(context, root);
    }

    @Override
    protected NameClassPair createObject(String strippedName, Object obj) {
      return new NameClassPair(strippedName, obj.getClass().getName());
    }
  }

  private static final class BindingEnumeration extends AbstractNamingEnumeration<Binding> {

    private BindingEnumeration(SimpleNamingContext context, String root) throws NamingException {
      super(context, root);
    }

    @Override
    protected Binding createObject(String strippedName, Object obj) {
      return new Binding(strippedName, obj);
    }
  }

}
